Frangible article composed of polystyrene and polyethylene waxes

ABSTRACT

The invention comprises fragile molded articles composed of compositions of polystyrene and polyethylene waxes, together with a lubricant or mold release agent, which articles are useful as targets in the practice of skeet shooting.

United States Patent [72] Inventors Thomas E. Nixon;

John A. Barber; Floyd B. Nagle, Midland,

Mich.

211 Appl. No. 711,509

[22] Filed Mar. 8, 1968 [45] Patented Jan. 12, 1971 [73] Assignee TheDow Chemical Company Midland, Mich. a corporation of Delaware [54]FRANGIBLE ARTICLE COMPOSED OF POLYSTYRENE AND POLYETHYLENE WAXES 8Claims, No Drawings [52] US. Cl 273/105.4, 260/285 [51] Int. Cl; F4lj9/16,

[50] Field ofSearch 272/56.6ss; 273/ 105.4, 105.5, (Styrene Digest),(Ethylene Digest); 260/28.5A, (inquired) Primary Examiner-Anton O.Oechsle Assistant ExaminerMarvin Siskind AttomeysGriswold & Burdick andRichard G. Waterman ABSTRACT: The invention comprises fragile moldedarticles composed of compositions of polystyrene and polyethylene waxes,together with a lubricant or mold release agent, which articles areuseful as targets in the practice of skeet shooting.

FRANGIBLE ARTICLE COMPOSED F POLYSTYRENE AND POLYETHYLENE WAXES Thisinvention concerns fragile molded articles composed low molecular weightpolystyrene and polyethylene waxes, together with a lubricant or moldrelease agent, which fragile articles are suitable for use as targets inpractice shooting.

It has now been foun? that compositions of low molecular weightpolystyrene and polyethylene waxes, together with a small amount of afatty acid sufficient to act as lubricant and mold release agent, canreadily becompression or injection molded to make fragile articlessuitable for use in practice shooting.

More specifically, the compositions consist essentially of from 96.7 to99.4 percent by weight of the polystyrene, from 0.5 to 3.0 percent byweight of the polyethylene wax and from 0.1 to 0.3 percent by weight ofa fatty acid having from 12 to 26 carbon atoms in the molecule. v

The polystyrene to be employed can have a molecular weight correspondingto a viscosity characteristic of from about 12 to about 30, preferablyfrom 15 to 25, centipoise as determined for a 30 weight percent solutionof the polystyrene in toluene at 25 C.

The polyethylene wax can be a polyethylene having a molecular weight offrom about 2,000 to 4,000. Such polyethylenes have (Brookfield)viscosities of from about 2,000 to 6,000 centipoise at 250 F. 121 C.)

The fatty acid can be an aliphatic monocarboxylic acid having from 12 to26 carbon atoms in the molecule. Among suitable fatty acids are lauricacid, myristic acid, palmitic acid, stearic acid, arachidic acid,behenic acid, lignoceric acid and cerotic acid. Mixtures of two or moreof said fatty acids can also be used. The fatty acids are preferablysaturated aliphatic acids, but monoethylenically unsaturated fatty acidssuch as dodecylenic, palmitic, oleic, ricinoleic, petroselinic,vaccenic, linoleic, linolenic, eleostearic, licanic, parinaric, tariric,gadoleic, arachidonic, cetoleic, erucic or selacholeic, acid or mixturesthereof with one another or with the aforementioned saturated fattyacids can also be used. I

The ingredients can be blended together in any usual way. For example,the polystyrene in granular or powdered form, the polyethylene inparticulate or in finely powdered form and the fatty acid, can be dryblended by tumbling a mixture of the ingredients in the desiredproportions in a suitable bender. The mixture of ingredients can be dryblended, compounded or mixed on compounding rolls, a Banbury mixer or ina plastics extruder.

In a preferred practice the ingredients are dry blended and fed to aplastics extruder wherein the materials are heated, pressed andmechanically worked and blended into a uniform product which is thenextruded and is cooled and cut to a granular form suitable for molding.7

ln molding the compositions either the dry blended or the melt blendedmixture of ingredients is employed to compression, injection, or screwinjection mold said material into articles suitable for a desiredpurpose, e.g. as discs or as half sphere shells which are usually gluedtogether to form balls suitable for use as targets in practice shooting.It may be mentioned that for use as targets two half sphere shells areadhered together by adhesive or solvent softening of the edges to formspheres.

The walls of the moldings suitable for use as targets in practiceshooting usually have a thickness of from about 0.01 to 0.03 inch,although somewhat greater or lesser wall thickness of the moldings canbe used to make fragile targets.

Small amounts of dyes, coloring agents, pigments and the like can beincorporated into the compositions to make molded articles preparedtherefrom more visible, are not required.

The following example illustrates ways in which the principle of theinvention has been applied but is not to be construed aslimitin itssco gpe EXAMPLE parts of EPOLENE, (a waxlike polyethylene having a molecularweight of about 2,500 together with 0.25 part of powdered stearic acid,was dry blended, then was fed to a plastics extruder wherein theingredients were heated, melted and blended into a uniform compositionand were extruded, cooled and cut or broken to a granular form. Portionsof the product were compression molded at a temperature of about 150 C.and 500 pounds per square inch pressure to form half sphere shells 2%inches in diameter having walls 0.025 inch thick. The molded half sphereshells were easily removed from the mold without sticking or breakage.Two molded half shell spheres were solvent welded to form a sphere. Thespheres were fragile objects, easily broken by dropping on the floor orby other impact. Test specimens of the spheres were shot with No. 12(mustard seed) shot shells fired from a 22 caliber smooth bore gun andwere found toreadily shatter into a great plurality of pieces upon beinghit. The fragile plastic spheres were useful targets for practice ofindoors shooting with pellets and fine shot..

In contrast, a similar formulation prepared molecular weight polystyrenehaving a viscosity characteristic of 34.6 centipoise and an Mw of about61,500 and a Mn of about 21,000 was unsatisfactory.

We claim:

l. A fragile article of manufacture comprising a molding having wallsbetween 0.01 and 0.03 inch thick, prepared from a composition consistingessentially of from 96.7 to 99.4 percent by weight of polystyrene havinga viscosity characteristic of from 12 to 30 centipoise as determined fora 30 weight percent solution of said polystyrene in toluene at 25 C.,from 0.5 to 3 percent by weight of a polyethylene having a viscositybetween 2,000 and 6,000 centipoise at 121 C., and from 0.01 to 0.03percent by weight of an aliphatic monocarboxylic acid having from 12 to26 carbon atoms in the molecule.

2. An article as claimed in claim 1 containing an orange dye.

3. An article as claimed in claim 1 when in the form of a disc.

4. An article as claimed in claim 1 when in the form of a hollow sphere.

5. An article of manufacture suitable for use as a target in practiceand competition shooting comprising a fragile hollow sphere having wallsbetween 0.01 and 0.03 inch thick prepared by molding half sphere shellsfrom a composition consisting essentially of from 96.7 to 99.4 percentby weight of polystyrene having a viscosity characteristic of from 10 to30 centipoise as determined for a 30 weight percent solution of saidpolystyrene in toluene at 25. C., from 0.5 to 3 percent by weight of apolyethylene having a viscosity between 2,000 and 6,000 centipoise at121 C. and from 0.01 to 0.03 percent by weight of an aliphaticmonocarboxylic acid having from 12 to 26 carbon atoms in the molecule,and adhesively forming two half sphere shells to one another.

6. An article as claimed in claim 5 containing an orange dye.

7. An article as claimed in claim 5 wherein the aliphatic monocarboxylicacid is stearic acid. l

8. An article as claimed in claim 5 wherein the aliphatic monocarboxylicacid is behenic acid.

from low

2. An article as claimed in claim 1 containing an orange dye.
 3. Anarticle as claimed in claim 1 when in the form of a disc.
 4. An articleas claimed in claim 1 when in the form of a hollow sphere.
 5. An articleof manufacture suitable for use as a target in practice and competitionshooting comprising a fragile hollow sphere having walls between 0.01and 0.03 inch thick prepared by molding half sphere shells from acOmposition consisting essentially of from 96.7 to 99.4 percent byweight of polystyrene having a viscosity characteristic of from 10 to 30centipoise as determined for a 30 weight percent solution of saidpolystyrene in toluene at 25* C., from 0.5 to 3 percent by weight of apolyethylene having a viscosity between 2,000 and 6,000 centipoise at121* C. and from 0.01 to 0.03 percent by weight of an aliphaticmonocarboxylic acid having from 12 to 26 carbon atoms in the molecule,and adhesively forming two half sphere shells to one another.
 6. Anarticle as claimed in claim 5 containing an orange dye.
 7. An article asclaimed in claim 5 wherein the aliphatic monocarboxylic acid is stearicacid.
 8. An article as claimed in claim 5 wherein the aliphaticmonocarboxylic acid is behenic acid.